Long vs short-term cap gains?

Not modeled; use your rate for the expected holding period.

Not modeled. AMT is complex—consult a tax professional.

Not included. Add buffer for states/localities that tax gains/ordinary income.

Not covered here; this is a basic spread/cap gains estimate.

No. This is a rough calculator only; talk to a qualified tax professional.

finance calculator

Stock Option Tax Estimator

Roughly estimate ordinary income/AMT on exercise and capital gains tax on sale for ISO/NSO stock options (non-advisory).

Results

Bargain element (spread × shares): $10,000
NSO ordinary income: $10,000
ISO AMT income: $0
NSO ordinary tax: $3,200
ISO AMT (est.): $0
Capital gains tax: $750
Total estimated tax: $3,950
Gross sale proceeds: $20,000
Net proceeds after tax & strike: $11,050

How to use this calculator

Select ISO or NSO and enter shares, strike, FMV at exercise, and sale price.
Enter estimated ordinary/AMT/cap gains rates.
See bargain element, ordinary/AMT impacts, cap gains, total tax, and net proceeds (after strike).

Inputs explained

Option type: ISO or NSO.
Shares: Shares exercised and sold.
Strike price: Exercise price per share.
FMV at exercise: 409A/market value when you exercise.
Sale price: Price when you sell the shares.
Tax rates: Your marginal ordinary, cap gains, and AMT rates for estimation.

How it works

Bargain element = (FMV − strike) × shares. NSO: spread taxed as ordinary. ISO: spread treated as AMT income. Capital gains = (sale price − FMV) × shares (long/short not modeled here).

Formula

Bargain = (FMV − Strike) × Shares
NSO ordinary = Bargain (taxed at ordinary)
ISO AMT = Bargain (est.) × AMT rate
Cap gains = (Sale − FMV) × Shares × Cap gains rate
Net = Sale proceeds − Strike × Shares − Total tax

When to use it

Sanity-check potential tax exposure on exercising/selling options.
Comparing ISO vs NSO tax treatment at a high level.
Previewing net proceeds for liquidity planning.

Tips & cautions

ISO holding periods and AMT rules are complex—this is a rough estimate. Consult a tax pro.
Cap gains timing (long vs short) affects rates; this uses a single cap gains rate for simplicity.
Local taxes and deductions aren’t modeled—add buffer if your locality taxes gains/ordinary income.
Not tax advice. Does not model holding periods (long vs short), QSBS, AMT credits, or local taxes.
Assumes immediate sale; does not model step-up or multi-stage sales.
Assumes flat rates; real tax situations vary widely.

Worked examples

1,000 ISO, $5 strike, $15 FMV, $20 sale, 32% ordinary, 15% cap gains, 28% AMT

Bargain = $10,000
ISO AMT ≈ $2,800
Cap gains tax ≈ $750
Total tax ≈ $3,550
Net ≈ $11,450

500 NSO, $2 strike, $10 FMV, $12 sale, 24% ordinary, 15% cap gains

Bargain = $4,000
Ordinary tax ≈ $960
Cap gains tax ≈ $150
Total tax ≈ $1,110
Net ≈ $4,390

Deep dive

This stock option tax estimator shows a rough view of bargain element, ordinary/AMT impact, capital gains tax, and net proceeds for ISO vs NSO exercises and sales. Non-advisory.

Use it to get a quick sense of potential taxes before talking to a tax professional.

FAQs

Long vs short-term cap gains?: Not modeled; use your rate for the expected holding period.
AMT credits for ISO?: Not modeled. AMT is complex—consult a tax professional.
Local taxes?: Not included. Add buffer for states/localities that tax gains/ordinary income.
QSBS or 83(b)?: Not covered here; this is a basic spread/cap gains estimate.
Is this tax advice?: No. This is a rough calculator only; talk to a qualified tax professional.

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Not tax advice. Simplified assumptions—consult a tax professional for your situation, holding periods, AMT, and local taxes.